Induction heat curable epoxy resin systems

Abstract

Epoxy resin systems readily available for curing by the application of an induction heat energy source comprising a silica-filled, low viscosity epoxy resin in combination with an iron oxide or a steel powder.

What is claimed is: 
     
       1. A composition consisting of (a) 4-50%, by weight, of a liquid epoxy resin having on average more than one epoxy group per molecule;   (b) 40-80%, by weight, of silica particles; and   (c) 10-50%, by weight, of a component responding to induction current selected from the group consisting of iron oxides, steel powder and mixtures thereof.   
     
     
       2. The composition of claim 1, wherein said epoxy resin has an epoxy equivalent weight of 150-500 g/equivalent and is an epoxy novolac resin, a polyglycidyl ether of a dihydric phenol, a polyglycidyl ether of a trihydric alcohol, a cycloaliphatic epoxy resin, a polyglycidyl ester, an epoxidized ester of a polyethylenically unsaturated fatty acid, an epoxidized ester of an unsaturated alcohol and an unsaturated carboxylic acid or an epoxidized polyethylenically unsaturated hydrocarbon. 
     
     
       3. The composition of claim 1, wherein said liquid epoxy resin is a reactive diluent-modified epoxy resin. 
     
     
       4. The composition of claim 2, wherein said epoxy resin is a diglycidyl ether of a dihydric phenol. 
     
     
       5. The composition of claim 1, wherein the particle size of at least about 90% of all of said silica particles is within 0.03-0.30 mm. 
     
     
       6. The composition of claim 1, wherein component (c) is gamma Fe 2  O 3 , magnetic Fe 3  O 4 , steel powder or mixtures thereof. 
     
     
       7. The composition of claim 6, wherein component (c) is steel powder wherein the particle size of at least about 90% of all of the steel particles is within 0.03-0.30 mm. 
     
     
       8. A composition consisting of (a) 4-50%, by weight, of a liquid epoxy resin having on average more than one epoxy group per molecule;   (b) 40-80%, by weight, of silica particles;   (c) 10-50%, by weight, of a component responding to induction current selected from the group consisting of iron oxides, steel powder and mixtures thereof; and   (d) a curing agent present in stoichiometric amounts ±50% relative to component (a).   
     
     
       9. The composition of claim 15, wherein said component (d) is a latent curing agent. 
     
     
       10. The product obtained by curing the composition of claim 8 by the application of an induction heat energy source thereto. 
     
     
       11. The product obtained by curing the composition of claim 9 by the application of an induction heat energy source thereto. 
     
     
       12. The composition of claim 8, wherein said epoxy resin has an epoxy equivalent weight of 150.500 g/equivalent and is an epoxy novolac resin, a polyglycidyl ether of a dihydric phenol, a polyglycidyl ether of a trihydric alcohol, a cycloaliphatic epoxy resin, a polyglycidyl ester, an epoxidized ester of a polyethylenically unsaturated fatty acid, an epoxidized ester of an unsaturated alcohol and an unsaturated carboxylic acid or an epoxidized polyethylenically unsaturated hydrocarbon. 
     
     
       13. The composition of claim 8, wherein component (a) is a reactive diluent-modified epoxy resin. 
     
     
       14. The composition of claim 12, wherein said epoxy resin is diglycidyl ether of a dihydric phenol. 
     
     
       15. The composition of claim 8, wherein the particle size of at least about 90% of all of said silica particles is within 0.03-0.30 mm. 
     
     
       16. The composition of claim 8, wherein component (c) is gamma Fe 2  O 3 , magnetic Fe 3  O 4 , steel powder or mixtures thereof. 
     
     
       17. The composition of claim 16, wherein component (c) is steel powder wherein the particle size of at least about 90% of all of the steel particles is within 0.03-0.30 mm.